Ten years to save Australia's Great Barrier Reef

TIME is not on our side: we have just 10 years to save the Great Barrier Reef.

That's according to Ove Hoegh-Guldberg at the University of Queensland in Brisbane, Australia. If we continue to release CO2 into the atmosphere at current rates, within a decade we will reach a tipping point beyond which ocean warming will occur no matter what we do, reducing the reef's chances of survival, he told delegates at the Greenhouse 2011 conference in Cairns this week.

Just six years ago the outlook was more optimistic. Biologists had found evidence that corals might cope with warmer oceans by swapping the symbiotic algae they rely on for their energy with versions that function efficiently at higher temperatures. But more recent studies have suggested that this is only an option for the 25 per cent of the world's coral species that host multiple species of algae rather than just one. The remaining species must "migrate their way out of trouble" instead, says Hoegh-Guldberg.

His calculations suggest that under current rates of warming, the corals must move southwards at a rate of 15 kilometres per year to stay cool. "Individual coral larvae can travel great distances, but the entire reef system can't," he says. "The uncomfortable conclusion is that we might lose the reef."

Lesley Hughes at Macquarie University in Sydney agrees. "There is virtually no evidence" that coral reefs can adapt fast enough to keep up with global warming, she says.

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